from every thing I've ever seen the Stereo Headphones > 5.1 's for gaming because the 3d sound field created is better on headphones with 2 speakers than 5.1. especially on a XFI system.
if you have 580's you would probably be best either doing something with the pc like getting a better sound card or putting a amp on the line to push the headset better.
Getting a AuzenTech X-FI Prelude 7.1 would be a example of a upgrade you would be able to count on if say your on a audigy 2.
the only real upgrades for headsets are from what i can tell are upgrading to a better quality set of can's which for me was a problem because im sorta behind the times on headphones. cans that were 400$ awhile ago can be had for like 150$ now lol which is a good thing i guess aside from the fact that they are old news now lol so if you know the good cans from the bad thats how you should choose imho.
Id almost always have to say forget anything that sounds gimmicky because is probably the only thing going for the unit.
its not that im against 5.1 headphones its just that every time ive used them they have
1 been weak on bass which for music sucks.
2 had what seemed like less quality speakers
3 not worked like my surround sound speakers setup not even close to as easy to determine where things are coming from.
4 not as loud as my sterio headsets
5 not as sensitive to low sounds either
6 like i said Xfi is great on stereo headsets
i just wish i could put more cash on even better set of hi-fi stereo headphones because you get what you pay for MOST TIMES
.